<?php
class A
{
   function foo()
   {
       if (isset($this)) {
           echo '$this is defined (';
           echo get_class($this);
           echo ")\n";
       } else {
           echo "\$this is not defined.\n";
       }
   }
}

class B
{
   function bar()
   {
       A::foo();
   }
}

$a = new A();
$a->foo();
A::foo();
$b = new B();
$b->bar();
B::bar();
?>
